The purpose of the research proposed here is to investigate ways in which to communicate cancer-related information through Cancer Information Service (CIS) telephone interactions and follow-up print materials that could increase its effectiveness in motivating subsequent behavior. The goal is to investigate whether the influence of CIS-delivered messages can be improved by framing them in gain (benefits) or loss (risks) terms and by tailoring them to individual differences in the psychological styles with which people process health-related information. These styles include individual variability in the willingness to (a) ponder complex arguments, (b) monitor the environment for threatening information, (c) feel motivated by accomplishment versus safety, and (d) attribute the responsibility for maintaining good health to oneself or to health professionals. Building on nearly a decade of research focused on optimizing messages concerning cancer prevention and early detection behaviors, ten experiments are proposed for the five-year project period. The first two experiments concern the framing in gain versus loss terms of CIS-delivered, proactive messages about fruit and vegetable consumption. Then, eight experiments tailor messages to the four health information processing strategies listed above. Four of the eight tailoring experiments target fruit and vegetable consumption among healthy callers to the CIS, and four encourage individuals with cancer to ask their physicians about available clinical trials. It is our hope that findings from this line of research will allow us to articulate clear principles for developing especially effective health messages.